Articles | Volume 14, issue 22
Biogeosciences, 14, 5069–5075, 2017
Biogeosciences, 14, 5069–5075, 2017

Research article 15 Nov 2017

Research article | 15 Nov 2017

Seagrass as major source of transparent exopolymer particles in the oligotrophic Mediterranean coast

Francesca Iuculano1, Carlos Maria Duarte2, Núria Marbà1, and Susana Agustí2 Francesca Iuculano et al.
  • 1Department of Global Change Research, Instituto Mediterráneo de Estudios Avanzados (IMEDEA), CSIC-UIB, Esporles, 07190, Balearic Islands, Spain
  • 2King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, 23955-6900, Saudi Arabia

Abstract. The role of seagrass, Posidonia oceanica, meadows as a source of transparent exopolymer particles (TEPs) to Mediterranean coastal waters was tested by comparing the TEP dynamics in two adjacent coastal waters in the oligotrophic NW Mediterranean Sea, one characterized by oligotrophic open-sea waters and the other accumulating seagrass leaf litter, together with an experimental examination of TEP release by seagrass litter. TEP concentrations ranged from 4.6 to 90.6 µg XG (xanthan gum) Eq L−1, with mean (±SE) values of 38.7 (± 2.02) µg XG Eq L−1 in the site devoid of seagrass litter, whereas the coastal beach site accumulating leaf litter had > 10-fold mean TEP concentrations of 487.02 (± 72.8) µg XG Eq L−1. Experimental evaluation confirmed high rates of TEP production by P. oceanica litter, allowing calculations of the associated TEP yield. We demonstrated that P. oceanica is an important source of TEPs to the Mediterranean Sea, contributing an estimated 76 Gg C as TEPs annually. TEP release by P. oceanica seagrass explains the elevated TEP concentration relative to the low chlorophyll a concentration in the Mediterranean Sea.

Final-revised paper